The smooth-running Inline 6 to be replaced?

http://www.dailytech.com/Fuel+Efficiency+is+King+Turbo+Four+to+Replace+BMWs+Naturally+Aspirated+Inline6/article20779.htm
"...BMW is now looking to make another leap in fuel efficiency, and it

means that the company's normally aspirated inline-6 could get the axe in
favor of a new 2.0-liter, turbocharged inline-4 engine. The new engine
produces 240hp @ 5,000 rpm and 260 lb-ft of torque at just 1,250 rpm...."

Torquey little bugger.
I would not be surprised if the NA I6 was obsoleted in favor of the
turbo 4. But you'll still be able to get a turbo I6.
For the foreseeable future, the engine bays will continue to be made
to hold the I6, and it will be offered as an option.
I would like see them continue to offer an NA I6 (with direct
injection, please!) as on option for those who favor the I6 smoothness
and refinement, and who don't need the turbo's extra power.
I've driven a recent 328. It was plenty fast, IMO.
I'd love to see a real, apples-to-apples fuel-economy comparison
between a direct-injected 3.0 I6 and the new 2.0 turbo 4. I'd bet the
difference would not be worth caring about, to many of us.

Yes but no standard 328 (even the 328iS) was as quick as the current
I6 330d so why flirt with fuel consumption hell for a slower car?

Absolutely.
But, if BMW *and* performance *and* fuel economy are requirements then
diesel is the way to do it IMHO. I'm not sure if the Americans have
spotted this one yet but the Europeans certainly have.
Yes the low capacity high output turbo petrol/gas engines are
interesting and have superb *tested* fuel economy *but* you will be
able to hear the fuel gushing into the cylinders if you try using that
power.

I think much of the point is just that the turbo system puts a lot more
stress on a lot more parts than a normally-aspirated engine that spends
most of its time just loping along anyway.
I've seen plenty of folks get 500,000 miles on the older BMW inline sixes.
The newer lubricant formulations help that a lot. I would be very surprised
to see anyone manage that with the 4-cylinder Kompressor engine.
You want performance in a small package, and you want efficiency, and
long-term reliability is going to be the price you'll pay. That seems to
be fine for most people who don't intend on keeping their cars for very long
anyway.
--scott

As a percentage very few cars indeed get anywhere near 500,000 miles
before being scrapped - my guess is the vast majority at way less than
half that. So is there any point in designing for that sort of life?

Well, there are a bunch of issues mixed up in this. First of all, as
lubrication improves, engines last longer. So it's possible that as
lubrication continues to improve, the high peformance 4-cylinder engines
might start lasting longer too.
Secondly, the point you bring up. In the sixties, GM did some studies
that basically determined their cars were lasting too long and people
were keeping old cars rather than buying profitable new ones. So some
serious engineering went into making the time to failure of all parts
of the vehicle about the same and about 80,000 miles. In the end, this
came to kill GM when the customer did start demanding a more durable
vehicle.
On the other hand, there are folks out there who get a new car every
year because they have to have the latest model. And there are also
a lot of people who seem to have a vehicle-totalling accident every
year too.
But, if people had cars that lasted longer, would they keep them? At
what point does maintenance cost exceed new car cost? I don't know any
of this. But then, I only have 480,000 miles so far.
--scott

Most engines outlive the car these days - unless they get damaged by a
broken can belt etc or a failed cooling system. They don't wear out as
once was the case. In the UK when I were a lad cars might have two
reconditioned engines fitted in its life. They wore out and started
burning lots of oil. The US with its generally larger lightly stressed
engines might have been different.

The buying pattern must be very different in the US. Here, most who could
afford a new car changed it regularly. Perhaps the majority of other than
small cars were bought initially by companies, and tax allowances made it
such that they'd be replaced every 3 years max. An 80,000 mile car would
have been at the end of its life anyway at perhaps 8 years old.

Given the average mileage in the UK of about 10,000 a year, your car would
date from the 60s/70s. And finding spares not easy. ;-)

I wouldn't worry about that... Sure, the motor has smaller size and
few cylinders to spread the power across, but that can all be
engineered-for. Plus, they are designed for fewer RPM's, both in
normal use and the redline, which must save wear...

Both, but mostly the latter as everything is stress that much more and you
have to trash the engine to get sparkly performance. The nice thing about
[big] BMW I6's and V8's is the good torque at moderate revs'

The turbo motors should need to be "thrashed" less, due to their
low-end torque. I think that's the whole point of them (fewer revs
for better efficiency).
Compare the 3.0L M54B30 with 231hp @ 5900 rpm and 220 lb-ft @ 3500 to
the new 2.0 turbo 4, with 240hp @ 5,000 rpm and 260 lb-ft of torque at
just 1,250 rpm.
Don't confuse old-school turbo motors with these new direct-injected
turbo motors...

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